How Do I Electronically Fire Windshield Wiper Actuation?

Hey guys, new here, but I've had my Prius for a while.

I am prototyping a computer-vision software that gives me a value based on the amount of rain on the windshield. I intend to connect it to my windshield wiper system and craft an API so it can interface with the car's wiper speed. I was figuring on using an optocoupler to complete a circuit, telling the car I've moved the wiper controller when I actually haven't. I really have no idea where to start on the car side of things though. I've never been much of a car guy, but I've installed aftermarket stereos, replaced a cv-axel, and a few other things, so I'm not totally incompetent with vehicular work, but I'm far from an enthusiast. I just don't want to start tearing things apart without knowing what I'm doing at least a little.

Can anyone recommend the least intrusive way I could connect a few wires with the intent to light up the rail or bridge a connection? I'd be happy to watch a video or read some documentation if anyone could recommend something. I just need a jumping off point from someone who's worked on wipers or prius electronics before.

Thank you so much in advance.